The goal of this proposal is to achieve an increased understanding of the etiology and treatment of idiopathic sudden hearing loss by the systematic collection and evaluation of clinical and serological data. Our objectives include the serologic evaluation of acute and convalescent sera for the purposes of identifying the principle virus(es) responsible for SHL, and the determination of the relationship between virally induced SHL to other pathological, demographic, or environmental factors. In addition, we will continue a collaborative clinical study at MEEI, WVU, and KP Oakland assessing the relationship of ISHL to hereditary, epidemiological, and occupational factors by means of statistical analysis of data obtained from ISHL patients. We will determine the correlation between electronystagmography, Hallpike caloric testing, vestibular and cochlear injury, and the etiology and degree of hearing loss and recovery from ISHL, as well as the role seasonal incidence plays in the onset of ISHL. The significance of these studies is to increase our understanding of the etiology, classification, and treatment of sudden hearing loss, as well as to lend further insight into the pathophysiologic mechanisms of sensori-neural hearing loss in general.